Crack interactions during dynamic loading on a hardened cement paste specimen
✍ Scribed by Itzhak Avnon; David Z. Yankelevsky
- Book ID
- 103070006
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- English
- Weight
- 481 KB
- Volume
- 42
- Category
- Article
- ISSN
- 0013-7944
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✦ Synopsis
Hardened
Cement Paste (HCP), like other rock-like materials, was found to fail through cracking. When a source of impulsive load is applied to a two-dimensional specimen, cracks are developed from the source to the boundaries and in other different directions. This paper is concerned with the description and explanation of these phenomena. It was found that the crack propagation direction is not arbitrary, but is influenced by the interaction of stress waves which are reflected from the specimen boundaries or from other stress wave fronts back to the source. These reflected stress waves cause spalling cracks parallel to the boundaries or to the wave interfaces. These spalling cracks interact with the main radial cracks developing from the source and may stop them. The length of the different cracks during the failure process depends on the time period needed to failure and on the values of the crack propagation velocity and the stress wave velocity. According to the different crack lengths, a ratio of 1: 3 (and even 1: 2) was found between the crack propagation velocity and the stress wave velocity. The measured average value of the crack propagation velocity is about 60-200 m/s. The stress wave velocity therefore has to be about 600 m/s, much lower than the elastic longitudinal wave velocity.